English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

OBJECTIVE The small diameter of cervical pedicles and a large transverse cervical pedicle angle are challenges that have led spinal surgeons to investigate how they could achieve a wider safety trajectory and reduce the insertion angle during cervical pedicle screw (CPS) placement. In this paper, the authors detail the advantages of using a curved pedicle probe and a laterally located entry point for overcoming these challenges. METHODS From March 2012 to May 2016, the authors performed posterior cervical fusions using CPSs on 119 consecutive patients. The lateral mass screw conversion and the CPS breach rate were analyzed. Using preoperative CT, it was determined that θ lat is similar to the anatomical pedicle angle, and θ med is the minimally acceptable medial angle. The actual insertion medial angle (θ ins ) was determined by postoperative CT. To identify how much of the medial angle on θ ins could be reduced from the anatomical pedicle angle (θ lat ), and how much closer to θ med , (θ ins -θ med ) / (θ lat -θ med ) was calculated. To verify shifting of the entry point and widening of the trajectory, the mean df/Df (i.e., shifted facet point/planned facet point) values were analyzed. RESULTS The total number of planed CPSs was 759, the conversion rate was 4.61% (35/759), and the accuracy rate was 95.9% (694/724). The authors could calculate that θ ins could be expected near the 90%, 80%, 80%, 80%, and 110% value of θ lat on C-3, C-4, C-5, C-6, and C-7 levels, respectively, with the (θ ins -θ med ) / (θ lat -θ med ) equation. The mean df/Df values were 0.64, 0.62, 0.63, 0.63, and 1.24 on the C3-7 levels, respectively. CONCLUSIONS Through the use of a curved pedicle probe and a laterally located starting point, the planned and laterally located entry point medial shift was made during CPS placement. The entry point shift yielded a wider, safe trajectory and reduced the burden of making a large medial angle, similar to an anatomical cervical pedicle lateral angle, for safe CPS placement without creating a funnel-shaped hole.

journal of neurosurgery. spine

Widening of the safe trajectory range during subaxial cervical pedicle screw placement: advantages of a curved pedicle probe and laterally located starting point without creating a funnel-shaped hole